Yes that's possible, I have a preset where I control something like the mix of delay in snapshot 1, the tempo of a tremolo in snapshot 2 and the wah in snapshot 4... all with Exp 1 . I just assigned the controller in stomp mode and then worked on the snapshots. The Exp 1 changes the value of all assigned parameter when the fx block is "on" in the chosen snapshot. That means, you can change this values even together when you switch on more than one assigned fx block at a time.
Did you remember to assign the a/b block to a controller? As I understood, the values / settings choosen in the home area can not be changed / saved from snapshot to snapshot unless you assign one controller to the value.
